The invention relates to a thrust-reversing nozzle assembly for a watercraft and, in particular, for a jet-propelled watercraft such as a sport boat or a personal watercraft.
As shown in FIG. 1, a personal watercraft 10 has a hull 12, a seat 14 configured to support up to four riders, and a steering control mechanism 16 (e.g., handlebars) with which the operator steers the watercraft. Typically, a personal watercraft is propelled by a waterjet thrust system, with the thrust-producing jet of water being expelled at relatively high velocity from a nozzle assembly 18 mounted at the rear of the watercraft 10. A thrust-directing nozzle member 22 is laterally pivotally mounted in the assembly so as to swing left and right (about a vertically oriented axis), which directs the jet of water left or right and causes the watercraft to turn in the same direction. In some cases, the nozzle member 22 may also be mounted so as to pivot vertically slightly up and down (about a horizontally oriented axis), thereby enabling the xe2x80x9cattitudexe2x80x9d of the watercraft within the water to be adjusted or xe2x80x9ctrimmed.xe2x80x9d When the steering control mechanism 16 is turned, an interconnected steering linkage 24 pushes and pulls on steering armature 26, which is connected to (e.g., integral with) the nozzle member 22, thereby effecting lateral pivoting of the nozzle member 22 and hence turning of the watercraft.
As shown in FIGS. 2A and 2B, a retractable reverse gate 30 (not shown in FIG. 1 for clarity) is attached to the rear portion of the hull of the watercraft and swings vertically between 1) a stowed or retracted position, shown in FIG. 2A, in which it is xe2x80x9ctuckedxe2x80x9d partially within the xe2x80x9cpocketxe2x80x9d or xe2x80x9ctunnelxe2x80x9d 20 formed by the rear portion of the hull (see FIG. 1) and in which the nozzle assembly 18 is mounted; and 2) a lowered or extended position, shown in FIG. 2B. In the stowed or retracted position (FIG. 2A), the reverse gate is held out of the way of the propulsive jet of water being expelled from the nozzle assembly 18, and therefore it does not affect the direction of travel of the watercraft. When it is desired to reverse the direction of travel, i.e., to back up, the reverse gate 30 is lowered (e.g., by pulling or pushing a reverse lever (not shown) that is accessible to the operator) by means of reverse gate linkage 31 into position behind the nozzle assembly 18, as shown in FIG. 2B. The reverse gate 30 has a xe2x80x9cshellxe2x80x9d configuration, with generally hemispherical or quarter-spherical inner surfaces over each of the portions 30a and 30b. Accordingly, when the water jet being expelled from the nozzle assembly strikes the inner surfaces of the reverse gate, it is deflected or turned so as to be expelled forwardly from the reverse gate, thereby effecting reverse movement of the watercraft.
As further illustrated in FIG. 2B, the nozzle member 22 typically is mounted (either directly or via a gimbal system to allow vertical, trim pivoting as well as lateral, steering pivoting) over the exit end of a flow-accelerating venturi member 28 having a narrowing, flow-accelerating interior passage that accelerates the jet of water. The venturi member 28, in turn, is mounted (e.g., bolted) to impeller housing 32, which is secured (e.g., bolted) to the pump support of the watercraft. A waterjet-producing impeller and the shaft which spins it are housed within and extend through the impeller housing 32, respectively.
What we have observed, however, is that the operator of the watercraft typically does not have the same level of directional control when travelling in a reverse direction as when travelling in a forward direction. In fact, it has been observed that, depending upon the desired radius of a reverse-direction turn, a xe2x80x9ccross-controlxe2x80x9d situation can arise in which the watercraft actually turns in the direction opposite to that in which it is desired to travel as the jet of water is deflected back not along the axis of the nozzle, but rather at a complementary angle to it. Additionally, we have found that in the prior art, if the nozzle member is vertically pivotable for adjusting the xe2x80x9ctrimxe2x80x9d of the watercraft, acceptable reverse travelling performance has not been obtained because changing the trim angle of the nozzle can cause 1) the reverse gate to be blown back up to the retracted position by the waterjet; 2) the waterjet to pass completely over the top of the reverse gate; 3) the waterjet to strike the reverse gate too far down on the inner surface to be diverted correctly; or otherwise to be misdirected. Accordingly, there exists a need in the art for an improved reversing assembly for use in waterjet-propelled watercraft such as a personal watercraft, particularly in such waterjet-propelled watercraft in which the nozzle member is capable of pivoting vertically as well as laterally for xe2x80x9ctrimmingxe2x80x9d the attitude of the watercraft in the water.
The present invention overcomes the limitations of the prior art described above and therefore meets this need. In particular, the invention features an improved reverse gate assembly in which the reverse gate is linked to the thrust-directing nozzle member so as to pivot laterally with it (i.e., left and right about a vertically oriented axis), particularly while permitting vertical (i.e., up and down about a horizontally oriented axis), trim-adjusting pivoting of the nozzle (which trim-adjusting pivoting causes the axis about which the reverse gate pivots to move in a vertical direction). This ensures that the net effect of the reversed flow of the waterjet is a reversing thrust force that is oriented substantially along the direction of the axis of the nozzle member; as the nozzle member pivots with steering inputs, the reverse gate also pivots so as to maintain that substantial alignment. Thus, steering sensitivity and control when travelling in the reverse direction are significantly improved as compared to the prior art.
In a first aspect, the invention features a nozzle assembly which is capable of reversing the traveling direction of a waterjet-propelled watercraft. The nozzle assembly includes a nozzle member that is configured to be connected to a rear portion of the watercraft, with the nozzle member being both laterally pivotable with respect to the watercraft (for steering control) and vertically pivotable with respect to the watercraft (to adjust the xe2x80x9ctrimxe2x80x9d or the attitude of the watercraft in the body of water in which it sits). The nozzle assembly further includes a laterally pivotable, retractible reverse gate that is linked to the nozzle member so as to pivot laterally with it. The reverse gate is movable between a stowed position and a thrust-reversing position in which it redirects a jet of water expelled from the nozzle member so as to reverse the traveling direction of the watercraft. (The reverse gate can also be held in a xe2x80x9cneutralxe2x80x9d position (which requires the operator to hold the actuating lever in a mid-position, between a reverse gate-stowed position and a reverse gate-extended position), in which xe2x80x9cneutralxe2x80x9d position the reverse gate deflects water straight downward so that the watercraft does not move forward or backward, e.g., when idling.) By being linked to the nozzle member so as to pivot laterally with it, the reverse gate always redirects the jet of water in the same direction relative to the nozzle member, i.e., in a direction such that the net thrust acts in a reversing direction.
In preferred embodiments of the nozzle assembly, the reverse gate is pivotally attached directly to the nozzle member and pivots vertically with respect to it. The nozzle assembly may include a flow-accelerating venturi member that is configured to be connected to the rear portion of the watercraft, or the nozzle assembly may be a retrofit assembly that is configured to be attached to a flow-accelerating venturi member that is already connected to the rear portion of the watercraft.
Preferably, the nozzle assembly is gimbaled, e.g., by mounting the nozzle member in a trim ring so as to pivot laterally within the trim ring and by having the trim ring configured to be mounted to the venturi member so as to pivot vertically relative to the venturi member, thereby enabling the nozzle member to pivot both laterally (for steering control) and vertically (to adjust the xe2x80x9ctrimxe2x80x9d of the watercraft). A reverse gate actuating bracket preferably is connected to the trim ring and is linked to the reverse gate by means of a linkage, which linkage effects simultaneous vertical pivoting of the reverse gate actuating bracket and the reverse gate. Preferably, the linkage includes a linkage member that is vertically pivotally connected to the reverse gate actuating bracket, a linkage member that is vertically pivotally connected to the reverse gate, and a connecting rod extending between and connecting the two linkage members, which connecting rod is, itself, laterally pivotally connected to both linkage members. More preferably, the linkage assembly is configured such that the points about which the reverse gate pivots laterally when extended and retracted are, respectively, generally aligned with the vertical axis about which the nozzle member pivots laterally when the nozzle member is in a neutral trim position.
The reverse gate preferably has a rib extending along the surface which faces the nozzle member, and the rib is preferably configured such that end portions of it extend further upstream into an oncoming jet of water being expelled from the nozzle member than a central portion of the rib does. Additionally, the reverse gate preferably is laterally asymmetric to compensate for vorticity in the jet of water being expelled from the nozzle member. In particular, the reverse gate preferably has differentially sized flow outlet vents on its two sides and/or the flow outlet vents are configured such that the flow through one is directed more forwardly than the flow through the other.
The nozzle assembly preferably includes a tension spring, and the location of the tension spring mounting points preferably is such that, when the nozzle assembly is installed on the watercraft, the tension spring holds the reverse gate in the retracted position when it is in the retracted position and such that the tension spring holds the reverse gate in the extended position when it is moved into the extended position.
In another aspect, the invention features a waterjet-propelled watercraft having a hull with a rear portion and a nozzle assembly attached to the rear portion of the hull, which nozzle assembly is constructed in accordance with the first aspect of the invention and preferably incorporates one or more features of the preferred embodiments thereof.
Although the actuating linkage assembly provides perhaps its greatest advantage in the context of a nozzle assembly in which 1) the reverse gate is connected directly to the nozzle member and pivots vertically with respect to the nozzle member and 2) in which the nozzle member is vertically pivotally mounted so as to be able to adjust the xe2x80x9ctrimxe2x80x9d of the watercraft (a configuration which can cause the horizontally oriented axis about which the reverse gate pivots to shift vertically as the nozzle member pivots vertically to adjust the trim position), the actuating linkage assembly has great utility in and of itself due to the enhanced freedom of pivoting motion of the various componentsxe2x80x94even in a nozzle assembly in which the nozzle member does not pivot vertically. For example, the configuration of the actuation linkage assembly provides a certain amount of xe2x80x9cplayxe2x80x9d or flexibility into the system. Therefore, the same actuating linkage assembly components could be used in otherwise differently configured nozzle assemblies, e.g., nozzle assemblies in which the relative angular positions of the reverse gate and reverse gate actuating bracket differ.
Thus, according to a third aspect, the invention features a nozzle assembly that is capable of reversing the traveling direction of a waterjet-propelled watercraft. The nozzle assembly includes a nozzle member that is configured to be connected to a rear portion of the watercraft, and the nozzle member is laterally pivotable with respect to the watercraft for steering control (but is not necessarily vertically pivotable). The nozzle assembly further includes a retractible reverse gate linked to the nozzle member so as to pivot laterally with the nozzle member and a vertically pivotable reverse gate actuating bracket that is linked to the reverse gate by means of a reverse gate actuating linkage that is configured to effect simultaneous vertical pivoting of the reverse gate actuating bracket and the reverse gate. The reverse gate actuating linkage includes an actuating bracket linkage member that is vertically pivotally connected to the reverse gate actuating bracket; a reverse gate linkage member that is vertically pivotally connected to the reverse gate; and a connecting rod extending between and connecting the actuating bracket linkage member and the reverse gate linkage member, with the connecting rod being laterally pivotally connected to both of the linkage members.
In preferred embodiments according to this aspect of the invention, the reverse gate actuating linkage is configured such that when the reverse gate is retracted, the point about which it pivots laterally is generally aligned with the vertically oriented axis about which the nozzle member pivots laterally when the nozzle member is in a neutral trim position, and when the reverse gate is extended, the point about which the reverse gate pivots laterally is also generally aligned with the vertically oriented axis about which the nozzle member pivots laterally when in a neutral trim position. (In the context of this aspect of the invention, if the nozzle member is not vertically pivotable to xe2x80x9ctrimxe2x80x9d the attitude of the watercraft, the set or given vertical angular position of the nozzle member is deemed to constitute the neutral trim position.)
In preferred embodiments, the reverse gate is pivotally attached directly to the nozzle member and pivots vertically with respect to it. The nozzle assembly may include a flow-accelerating venturi member to which the nozzle member is connected, or the nozzle assembly may be a retrofit assembly which is configured to be attached to a pre-existing flow-accelerating venturi member that is connected to the rear portion of a watercraft. Furthermore, in preferred embodiments, the nozzle member is gimbaled such that the nozzle member pivots laterally and does, in fact, pivot vertically.
The reverse gate preferably has a rib extending vertically along its inner surface which faces the nozzle member, which rib is configured such that end portions of it extend further upstream into an oncoming jet of water being expelled from the nozzle member than a central portion of the rib does. Furthermore, the reverse gate preferably has flow outlet vents formed in its sidewalls, with the flow outlet vents being differentially sized such that more water flows through one than through the other and/or with the flow outlet vents being configured such that water passing through one is directed more forwardly than water passing through the other.
A tension spring preferably is provided, with the attachment points being configured such that when the reverse gate is in its retracted position, the tension spring holds it in the retracted position, and when the reverse gate is in its extended position, the tension spring holds it in the extended position.
In another aspect, the invention features a waterjet-propelled watercraft incorporating a nozzle assembly constructed according to the third aspect of the invention and preferably incorporating one or more features of the preferred embodiments thereof.
In a fifth, broader or more fundamental aspect, the invention features a pivotal apparatus assembly. The apparatus includes a first pivoting member that is pivotal about a first pivot axis and a second pivoting member that is pivotal about a second pivot axis that is spaced from the first pivot axis. The second pivot axis (1) swings or pivots in a plane parallel to the first pivot axis through a range of angles with respect to the first pivot axis; and (2) moves in a direction normal to that parallel plane through a range of displacement distances relative to the first pivot axis. The apparatus further includes an actuating linkage assembly connecting the first and second pivoting members in a manner such that pivoting of the first pivoting member about the first pivot axis effects driven pivoting of the second pivoting member about the second pivot axis, and furthermore, the actuating linkage assembly is configured such that such driven pivoting results for any angular position of the second pivot axis within the range of angles through which the second pivot axis swings or pivots and for any displacement distance of the second pivot axis relative to the first pivot axis and within the range of displacement distances.
In preferred embodiments (e.g., in which the pivotal apparatus forms a water jet-propelled watercraft nozzle assembly), the linkage assembly includes a first linkage member that is pivotally attached to the first pivoting member and which pivots about a first linkage member pivot axis that is spaced from and extends parallel to the first pivot axis; a second linkage member that is pivotally attached to the second pivoting member and which pivots about a second linkage member pivot axis that is spaced from and extends parallel to the second pivot axis; and a connecting member that extends between and connects the first and second linkage members, with the connecting member being pivotally connected to the first linkage member at a first pivot point and pivotally connected to the second linkage member at a second pivot point. Furthermore, the first and second pivot points preferably are spaced from the first linkage member pivot axis and the second linkage member pivot axis, respectively.
According to a sixth broad or fundamental aspect of the invention, it is not necessary for the second pivot axis to move in a direction normal to the plane in which it swings or pivots. Thus, according to this aspect of the invention, the invention features pivotal apparatus including a first pivoting member that is pivotal about a first pivot axis and a second pivoting member that is pivotal about a second pivot axis that is spaced from the first pivot axis. The second pivot axis pivots in a plane parallel to the first pivot axis through a range of angles with respect to the first pivot axis. The apparatus further includes an actuating linkage assembly that connects the first and second pivoting members such that pivoting of the first pivoting member about the first pivot axis effects driven pivoting of the second pivoting member about the second pivot axis, and the actuating linkage assembly is configured such that the driven pivoting results for any angular position of the second pivot axis within the range of angles. In particular, the actuating linkage assembly includes a first linkage member that is pivotally attached to the first pivoting member and pivots about a first linkage member pivot axis that is spaced from and extends parallel to the first pivot axis; a second linkage member that is pivotally attached to the second pivoting member and which pivots about a second linkage member pivot axis that is spaced from and extends parallel to the second pivot axis; and a connecting member that extends between and connects the first and second linkage members, with the connecting member being pivotally connected to the first and second linkage members at respective first and second pivot points.
In preferred embodiments (e.g., in which the pivotal apparatus constitutes a nozzle assembly for use in a waterjet-propelled watercraft), the first pivot point is spaced from the first linkage member pivot axis and the second pivot point is spaced from the second linkage member pivot axis.
According to a seventh aspect of the invention, the invention features a reverse gate for reversing the traveling direction of a waterjet-propelled watercraft. The reverse gate, which includes a pair of sidewalls for connecting the reverse gate to the rear portion of the watercraft and a rear wall extending between the pair of sidewalls, is laterally asymmetric so as to compensate for vorticity in the waterjet.
In preferred embodiments, the reverse gate has a vertically extending median rib which faces into the oncoming waterjet, which rib is configured such that the end portions of it extend further upstream into the oncoming jet of water than a central portion of the rib does. Furthermore, the reverse gate preferably has flow outlet vents formed in the sidewalls, and the flow outlet vents are differentially sized and/or differentially configured so as to direct more water through one flow outlet vent than through the other flow outlet vent and/or so as to direct water flowing through one flow outlet vent more forwardly than water flowing through the other flow outlet vent.
In another aspect, the invention features a waterjet-propelled watercraft incorporating a reverse gate that is laterally asymmetric so as to compensate for vorticity in the waterjet.
In a further aspect, the invention features a method of operating a waterjet-propelled watercraft in a body of water. The method includes selecting a trim angle of the waterjet from a range of possible trim angles to control the attitude of the watercraft in the body of water; redirecting the waterjet so as to produce a propulsive force acting to propel the watercraft in a reverse direction; and laterally pivoting the waterjet to steer the watercraft and simultaneously controlling the redirecting of the waterjet such that as the waterjet pivots laterally, the direction in which the waterjet is redirected, copivots laterally therewith.